1. Field of the Invention
The invention relates to a building board and, in particular, a flooring panel of wooden material, plastic or a mixture of wooden material and plastic, with a top side and an underside and side edges, for which a polyurethane layer is applied at least on the top side.
2. Discussion of Background Information
Known flooring panels are based largely on wooden material bodies of HDF, MDF or OSB. Panels of this type have disadvantages, since wooden materials have hygroscopic properties, whereby changes in the size of the wooden materials result from swelling and shrinking. As such, floor panels of this type cannot be used in wet rooms.
In addition, flooring panels are often provided with hard, wear-resistant surfaces which produce bothersome noises when walked on and counteract the natural effect that laminate floors are intended to produce.
Flooring panels with a base material made of water-resistant material, e.g., plastic, are also known. However, such plastic materials cannot be impressed with resin-impregnated decorative and overlay papers under increased pressure and under increased temperature.
Laminates are also known, onto the plate-like basis of which at least one paper layer bearing a pattern is applied. The pattern imitates in look and feel a natural material, such as, e.g., wood or stone. To this end, the pattern can also have an embossed structure. The cost-intensive production through the use of decorated and impregnated paper layers and their precise alignment on the plate-like base and their precise alignment with respect to a tool applying the embossed structure are disadvantages. The control of the pressure and temperature conditions and the control of the process speed are also cost-intensive.
In known panels, the imitated decoration is printed on a paper web that is subsequently coated with synthetic resin and rolled up on a roll. The prefabricated decorative web is subsequently applied onto wood fiber boards at the panel manufacturer. However, the dimensions of the paper web change through the printing of the pattern onto the paper web, the subsequent sealing of the paper web with synthetic resin and the subsequent joining of the decorative layer to the wooden material board through the effect of pressure and temperature. This is known by those of skill in the art as paper growing. The paper grows both in length (length growth) and in width (width growth).
If the decorative board is cut to size to form individual panels, the length and width growth must be taken into account, since otherwise there would be an unequal distribution of the pattern on the individual panels. The consequence of this would be that the floor composed of an unequally distributed decorative layer would have jumps (e.g., not align) in the pattern at the joining edges of the panels. Even if such jumps in the pattern amount only to a few millimeters, they stand out when viewed, which has a detrimental effect on the aesthetic impression and therefore reduces the quality of the laid floor. In order to be able to produce floors with a suitable quality, the paper growth must be registered and the cutting mechanism (e.g., saw) must be adjusted appropriately, which makes the production of the panels even more expensive.